A known latch mechanism is disclosed in Japanese Patent Laid-Open Publication published as No. 08-333938 and shown in accompanying drawing figures FIG. 5 and FIG. 6.
In the known latch mechanism, a reinforcing shaft 92 is provided near an engaging portion at which an edge portion of a leg portion 90a of a latch 90 engages with a pawl portion 91a of a locking plate 91. When an impact load is applied in a direction of the axis of a striker 93 (in the upright direction in FIG. 5 and the upper direction in FIG. 6), the latch mechanism being in a condition as shown in FIG. 5 is deformed as follows.
Firstly, the leg portion 90a moves in the upper direction in FIG. 6 and engages with a cover plate 94. As a result, a certain portion of the cover plate 94 at which the leg portion 90a contacts deforms upheaving in the upper direction in FIG. 6. In accordance with the upheaval of the cover plate 94, the reinforcing shaft 92 deforms and leans in a direction shown with an arrow S in the right side of FIG. 6. In accordance with the deformation of the reinforcing shaft 92, the base plate 95 also deforms, as a result, a bolt 96 supporting the locking plate 91 also deforms and leans in a direction shown with an arrow S in the left side of FIG. 6. Finally, the pawl portion 91a of the locking plate 91 moves in the lower direction in FIG. 6. In other words, the leg portion 90a moves in a counter direction of the movement of the pawl portion 91a. Thus, the striker 93 becomes easily disengaged from the latch 90 due to a clearance generated by such deformations between the leg portion 90a and the pawl portion 91a. 
The present invention therefore seeks to provide a latch mechanism wherein a striker is hardly disengaged from a latch.